Digital video content can now be streamed to multiple clients in real-time over traditional cable television and telephone networks, both of which are being leveraged by service providers to provide more attractive and varied services to customers. The streaming of digital video content to clients is supported by a stream server. A stream server delivers digital video content to a client via multicasting or unicasting, where multicasting is used to distribute the same content to multiple clients concurrently and unicasting is used to provide specific content to a particular client. The clients receive streams of digital video content via multicasting or unicasting and playout the digital video content to a device such as a television.
Most streaming networks include multiple stream servers and the load of streams to the clients is distributed among the stream servers. Various operating conditions within the network (e.g., resource failures and subscriber use patterns) cause the load on each stream server to continuously change. Further, it often necessary to take a stream server out of service for maintenance, upgrades, etc. In conventional streaming networks, once a stream is set up on a particular stream server, the stream is committed to that stream server for the life of the stream session. In order to take a stream server out of service, all active streams must run to completion or the streams must be prematurely terminated. Requiring all active streams to run to completion or be prematurely terminated before a stream server can be taken out of service makes it difficult to create windows for stream server maintenance.
In view of this, what is needed is a technique for streaming digital video content to a client that enables active streams to be transitioned between stream servers.